Light emitting diodes (LED) are frequently encapsulated within an epoxy based polymer. The polymer generally completely encapsulates the LED chip and bond wire. The polymer typically contains ultraviolet (UV) light inhibitors and thermally conductive fillers to reduce degradation of transmissivity caused by heat and light damage to the polymer. Heat also leads to delamination of the polymer, which causes the LED to function less effectively or not at all.
Traditional encapsulation methods such as injection molding require stringent design parameters such as temperature, viscosity, and volume to ensure proper flow characteristics of the polymer. The stringent design parameters restrict polymer components and additives that may be used. Hence, certain components and additives that may otherwise be beneficial to the longevity or efficiency of the light emitting device cannot be used because they would result in a polymer outside of the stringent design parameters. Alternatively, if certain additives or components are used in traditional methods, they may slow or complicate the encapsulation process.